Rolling mill stand for rod-shaped objects

Abstract

A rolling mill stand for rod-shaped objects, comprising a structure in which three work rolls (3, 3') are arranged, wherein one work roll (3') has a vertical axis of rotation (X); wherein the structure of the rolling mill stand is provided at the top with a first surface cavity (40) which opens at an upper end edge (55) of the structure, on the entry side of the rolling mill stand in the respective rolling mill compartment; wherein the first surface cavity (40) is arranged on the entry side opposite the side on which the work roll (3') is arranged with respect to a first vertical centre line plane of the rolling mill stand, which is parallel to the horizontal rolling direction (Y); and wherein the first surface cavity (40) is delimited at a distance from the first vertical centre line plane by a first wall (41) which is adapted to abut against at least one respective first central abutment (22) which is arranged in the upper part of the rolling mill compartment.

Description

Technical Field

[0001] This invention relates to the technical field of producing rod-shaped products by rolling, such as rods, bars, or similar products, but also including hollow tubular products, and therefore especially tubes. Specifically, this invention relates to a rolling mill stand with three rolls, adapted to be inserted laterally into a compartment of the rolling mill relative to the longitudinal axis of the mill. Background Technology

[0002] Various types of rolling mills are known. These include, for example, sizing mills, tension reducing mills, and extraction sizing mills.

[0003] To simplify stand changing operations, the mill is designed with a stand featuring three motorized rolls, each rotating about an axis of rotation and tilted 120° relative to the others. The first roll has a vertical axis of rotation actuated by a vertical axis adapter located above the stand. The second roll is operably positioned above a horizontal reference plane containing the rolling axis, while the third roll is operably positioned below the horizontal reference plane. Adapters for the second and third rolls are operably mounted below the support surface of the mill stand.

[0004] For this type of mill stand, each pair of subsequent and adjacent stands includes an "even-number" stand and an "odd-number" stand, wherein when rotated 180° about a vertical axis passing through the center of rolling, the roll arrangement of the odd-number stand corresponds to the roll arrangement of the even-number stand.

[0005] However, this mill stand configuration presents several challenges, such as alignment issues between multiple subsequent mill stands, proper maintenance of the rolling shafts after the stands are inserted into the corresponding compartments of the mill, differential wear of the work rolls due to misalignment, its cooling system, potential interference between mill stands or between a mill stand and its corresponding compartment when inserting or removing one of the stands into the mill, and the operational complexity of replacing certain wear-prone components such as slides and rollers.

[0006] Regarding the alignment of mill stands along the rolling axis after the stands are laterally inserted into the corresponding compartments of the mill, a particular problem arises because the mill stands may rotate about their vertical axis during their insertion and translation into the compartments. This can lead to misalignment between stands along the rolling axis and potentially interlocking issues between rolled products from two subsequent stands. Furthermore, it can cause uneven distribution of thermal expansion within the mill stands.

[0007] The first drawback associated with the cooling system is that, in order to cool the work rolls and thus maintain the predetermined temperature of the rolled product, the cooling system for each mill stand is extremely complex and almost entirely housed within the mill stand's structure. These aspects result in high production costs for the mill stand and also lead to high maintenance time and costs due to the difficulty for operators to access the various components of the cooling system.

[0008] The second drawback related to the cooling system is that its configuration allows coolant to be sprayed or injected along the entire thickness of the mill stand, which often leads to overcooling of the rolled product.

[0009] A third drawback related to the cooling system is that it has hydraulic joints and connectors that protrude outward from the mill stand structure and require manual operator intervention to connect the hydraulic connectors to the coolant supply circuit located in the mill frame that houses the mill stand.

[0010] The fourth drawback related to the cooling system is that the coolant jets or blades produced by this system can interfere with each other, thereby reducing cooling efficiency.

[0011] Conversely, regarding the potential interference between mill stands or between a mill stand and its corresponding compartment when inserting or removing one of the mill stands into or from the mill, known mill stands have multiple components protruding from the structure of the stand itself, which increases the risk of interference or necessitates disassembly and subsequent reassembly. These components include, for example, eye bolts for moving the stand outside the mill stand by a crane, and / or hydraulic joints and connections.

[0012] In addition, another known drawback of rolling mill stands is that some easily worn parts, especially the stands' wheels, require a long time to replace.

[0013] Based on the above considerations, a novel rolling mill stand is needed to overcome the aforementioned shortcomings. Utility Model Content

[0014] The main objective of this invention is to provide a mill stand that is configured to prevent any rotation about its vertical axis during the lateral insertion of the stand into the corresponding compartment of the mill (which would result in misalignment of the stand along the rolling axis), particularly by means of a suitable device adapted to hold the stand in the correct position.

[0015] Another objective of this invention is to provide a rolling mill stand equipped with a cooling system that is simple in construction and is almost entirely located outside the structure of the rolling mill stand, thereby helping to reduce the production cost, maintenance time and cost of the rolling mill stand, as the operator can easily access the various components of the cooling system.

[0016] Another objective of this invention is to provide a rolling mill stand equipped with a cooling system, the structure of which can prevent over-cooling of the rolled product.

[0017] Another objective of this invention is to provide a rolling mill stand equipped with a cooling system that is more efficient than known systems.

[0018] Another object of this invention is to provide a mill stand configured to avoid interference with the corresponding mill compartment or adjacent mill stands during insertion into or removal from the mill.

[0019] Another objective of this invention is to provide a mill stand constructed such that no operator intervention is required to connect its hydraulic connections to a coolant supply circuit located within the mill stand.

[0020] Another objective of this invention is to provide a rolling mill stand with a construction that allows for easy and quick replacement of some wear-prone parts (especially the wheels of the stand).

[0021] This invention achieves at least one of these objectives by means of a rolling mill stand for rod-shaped objects, as well as other objectives that are obvious from this specification.

[0022] The mill stand includes a structure in which three work rolls are arranged at 120° to each other, thereby defining a channel (5) for rolling the bar-shaped object in a horizontal rolling direction (Y). Among them, one of the three working rollers has a vertical axis of rotation X; The structure of the rolling mill stand has a first surface cavity at the top. The first surface cavity opens at the upper edge of the structure and is positioned on the entrance side of the rolling mill stand, and is transverse to the rolling axis of the rolling mill in the corresponding rolling mill compartment. The first surface cavity is arranged on the inlet side of the mill stand, opposite to the side where the aforementioned work roll is located. The work roll has a vertical axis of rotation. The first vertical centerline plane of the work roll is arranged on the side of the mill stand, and the first vertical centerline plane is parallel to the horizontal rolling direction Y. Furthermore, the first surface cavity is defined by a first wall near the first vertical centerline plane, the first wall being adapted to abut against at least one corresponding first central abutment portion disposed on the upper part of the rolling mill compartment; Wherein, the length of the first wall is equal to at least 2 / 3 of the thickness of the mill stand as measured along the horizontal rolling direction.

[0023] Another aspect of this utility model relates to a rolling mill for rolling bar-shaped objects, the rolling mill defining a rolling axis and comprising a rolling mill assembly having at least two rolling mill stands as described above.

[0024] Further features and advantages of the present invention will become more apparent from the detailed description of exemplary, but not exclusive, embodiments.

[0025] The dependent claims describe specific embodiments of the present invention. Attached Figure Description

[0026] In the description of this utility model, reference is made to the accompanying drawings, which are provided in an interpretive rather than limiting manner, wherein: Figure 1 A first perspective view of a rolling mill stand according to the present invention is shown; Figure 2 It shows Figure 1 An enlarged view of the upper part of the rolling mill stand; Figure 2a and 2b A cross-sectional view of a portion of the cooling system of a rolling mill stand according to the present invention is shown; Figure 3 It shows Figure 1 An enlarged view of the lower part of the rolling mill stand; Figure 4 It shows Figure 1 Second perspective view of the rolling mill stand; Figure 5 A partial cross-sectional side view of the mill stand according to the present invention is shown inside the mill. Figure 6 It appeared Figure 5 Enlarged view at the bottom; Figure 7 It appeared Figure 5 Enlarged view at the top; Figure 8 An example of a rolling mill including multiple rolling mill stands according to the present invention is shown; Figure 9 It shows Figure 8 A first side view of a partial cross-section of the rolling mill; Figure 10 It shows Figure 8 The second side view of the rolling mill; Figure 11 and Figure 12 The side views of the rolling mill compartments are connected, with one role in an extended position, i.e., connected to the corresponding roll, and the other role in a retracted position to allow the rolling mill to be withdrawn.

[0027] The same reference numerals indicate the same elements or parts. Detailed Implementation

[0028] Referring to the accompanying drawings, some examples of rolling mill stands according to the present invention are shown.

[0029] In all embodiments of this utility model, the mill stand includes a structure in which three work rolls 3, 3' are arranged at 120° to each other, thereby defining a channel 5 that defines a horizontal rolling direction Y for rolling a rod-shaped object.

[0030] One of the three working rollers, 3', has a vertical axis of rotation X, while the other two working rollers 3 have axes of rotation that are inclined at +30° and -30° respectively relative to a horizontal reference perpendicular to the vertical axis passing through the center of the channel 5.

[0031] The rolling mill stand according to this invention is of the type capable of withstanding the separation force (i.e., the force generated due to rolling) without the aid of external actuators (such as hydraulic chambers or pressing devices). Therefore, it is a rolling mill stand without roller frames.

[0032] Advantageously, the mill stand structure has a first surface cavity 40 at the top, which opens at the upper side edge 55 of the structure, preferably parallel to the horizontal rolling direction Y, arranged on the entrance side of the mill stand, transverse to the rolling axis of the mill, and located in the corresponding mill compartment. To prevent any slight rotation of the mill stand about its vertical axis when it is transversely inserted into the corresponding mill compartment, thereby avoiding misalignment of the stand along the rolling axis and uneven distribution of thermal expansion, the aforementioned first surface cavity 40 ( Figure 1 and Figure 2 The work roll 3' is arranged on the inlet side of the mill stand, which is opposite to the stand side where the aforementioned work roll 3' is located. The work roll 3' is arranged on the stand side relative to the first vertical centerline plane of the mill stand, which is parallel to the horizontal rolling direction Y.

[0033] The first surface cavity 40 is defined by a first wall 41 near the first vertical centerline plane, preferably but not necessarily parallel to the horizontal direction Y, and is adapted to abut against at least one first central abutment portion 22 disposed on the upper part of the mill compartment during the transverse insertion of the stand into the mill compartment. Figure 5 and Figure 7 ).

[0034] To optimize the above-mentioned technical effect, the length of the first wall 41 measured along the horizontal rolling direction Y is at least two-thirds of the mill stand thickness T measured along the horizontal rolling direction Y. Figure 2 ).

[0035] The first wall 41 can be flat and parallel to the first vertical centerline plane of the rolling mill stand. In this case, the first center abutment portion 22 also has a corresponding flat abutment surface.

[0036] It cannot be ruled out that the first wall 41 may be at least partially not parallel to the first vertical centerline plane.

[0037] For example, the first wall 41 may be inclined relative to the first vertical centerline plane, or it may have a stepped profile or other shaped profile. In these cases, the first central abutment portion 22 has a corresponding side that defines a corresponding abutment surface having an inclination or profile complementary to the inclination or profile of the first wall 41, respectively.

[0038] Preferably, the structure of the rolling mill stand also includes a second surface cavity 40' at the bottom. Figure 3 The cavity opens at the lower edge 55' of the structure, which is on the same side as the upper edge 55, and is defined by the second wall 41' near the first vertical centerline plane and parallel to the horizontal rolling direction Y. It is preferably arranged on the same plane as the first wall 41, and is adapted to abut against at least one second center abutment portion 22' disposed at the lower part of the mill compartment. Figure 5 and Figure 6 ).

[0039] In the same case, the length of the second wall 41' measured along the horizontal rolling direction Y is equal to at least two-thirds of the mill stand thickness T measured along the horizontal rolling direction Y, and preferably equal to the length of the first wall 41.

[0040] Similar to the first wall 41, the second wall 41' can be flat and parallel to the first vertical centerline plane of the rolling mill stand. In this case, the second central abutment portion 22' also has a corresponding flat abutment surface.

[0041] It cannot be ruled out that the second wall 41' may be at least partially not parallel to the first vertical centerline plane.

[0042] For example, the second wall 41' may be inclined relative to the first vertical centerline plane, or it may have a stepped profile or other shaped profile. In these cases, the second central abutment portion 22 has a corresponding side that defines a corresponding abutment surface having an inclination or profile complementary to the inclination or profile of the second wall 41'.

[0043] The first surface cavity 40 and the second surface cavity 40' can, but do not have to, be symmetrical about the horizontal plane.

[0044] In one variant ( Figure 2A first recess or seat 72 is formed on the first wall 41, wherein a first coating element 73, for example, in the shape of a parallelepiped, is securely fixed, the first coating element being adapted to abut against the first central abutment 22. Preferably, the first coating element 73 protrudes into the first surface cavity 40 with its outermost side 81 relative to the first recess 72, the side 81 serving as an abutment surface.

[0045] Preferably, but not necessarily, the outermost 81 is arranged parallel to the first vertical centerline plane of the mill stand and parallel to the horizontal rolling direction Y, serving as a flat abutment surface. In this case, the first central abutment portion 22 also has a corresponding flat abutment surface.

[0046] It cannot be ruled out that the outermost 81 may be at least partially not parallel to the first vertical centerline plane.

[0047] For example, the outermost 81 may be inclined relative to the first vertical centerline plane, or it may have a stepped profile or other shaped profile. In these cases, the first central abutment portion 22 has a corresponding side that defines a corresponding abutment surface having an inclination or profile complementary to the inclination or profile of the outermost 81.

[0048] Similarly, when the second surface cavity 40' is located at the bottom (FIG. 3), a second recess or seat 72' is obtained on the second wall 41', in which a second coating element 73', for example in the shape of a parallelepiped, is fixed and adapted to abut against the second central abutment 22'. Preferably, the second coating element 73' protrudes into the second surface cavity 40' with its outermost side 81' relative to the second recess 72', which serves as the abutment surface.

[0049] Preferably, but not necessarily, the outermost 81 is arranged parallel to the first vertical centerline plane of the rolling mill stand, serving as a flat abutment surface. In this case, the second central abutment portion 22' also has a corresponding flat abutment surface.

[0050] In this variant, the outermost 81, 81' or flat adjacent surfaces of the coating elements 73, 73' are arranged on the same vertical plane parallel to the first vertical centerline plane.

[0051] It cannot be ruled out that the outermost 81 may also be at least partially not parallel to the first vertical centerline plane.

[0052] For example, the outermost 81 may be inclined relative to the first vertical centerline plane, or it may have a stepped profile or other shaped profile. In these cases, the second central abutment portion 22' has a corresponding side that defines a corresponding abutment surface having an inclination or profile complementary to the inclination or profile of the outermost 81'.

[0053] Preferably, the length of the first coating element 73, measured along the horizontal rolling direction Y, and the length of the possible second coating element 73', are at least one-third of the mill stand thickness T, measured along the horizontal rolling direction Y.

[0054] The coated elements 73, 73' are preferably made of a material with a higher hardness than the material of the mill stand structure to improve their durability and contact precision. Examples of usable materials include steels such as C40, C50, and 42CrMo4, wear-resistant steels with a nominal hardness of 400-500 HBW (e.g., Hardox 400 or Hardox 500), and CORC®-g composite steel, whether or not they are surface hardened by heat treatment.

[0055] The shape of the coating elements 73 and 73' can be selected to facilitate their maintenance or replacement.

[0056] As shown in Figure 2, a first surface cavity 40 is formed along approximately half of the flat upper surface 70 of the structure, while another surface cavity can be formed in the other half, from which the upper end of the shaft of the work roller 3' with a vertical axis of rotation protrudes.

[0057] Similarly, the second surface cavity 40' is formed along approximately half of the flat lower surface 80 of the structure.

[0058] In a first embodiment of the rolling mill stand of this utility model, a cooling system is preferably provided on at least one surface of the rolling mill stand perpendicular to the horizontal rolling direction Y, comprising: - Hydraulic connection device 47, for introducing coolant into the rolling mill stand, is arranged in the upper part of the structure. A set of three supply devices 49, 50, 51 for supplying coolant from hydraulic connection device 47 to each work roll 3, 3', each supply device 49, 50, 51 being arranged on at least one surface near the corresponding work roll 3, 3'.

[0059] The first supply device 49 is located near and connected to the hydraulic connection device 47. Two pipes 52 and 53 are arranged outside the at least one face and branch off from the first supply device 49, respectively connecting the first supply device 49 to the second supply device 50 and the third supply device 51.

[0060] The cooling system is simple in construction and is located almost entirely outside the mill stand structure. As a result, the operator can easily access all the components of the cooling system, which helps to reduce the production cost, maintenance time and cost of the mill stand.

[0061] In addition, coolant (usually water) is supplied to the work rolls near at least one face of the mill stand.

[0062] Preferably, the three supply devices 49, 50, 51 and pipes 52, 53 of the set protrude at least partially from the flat surface of at least one side of the rolling mill stand.

[0063] In any case, the three supply devices 49, 50, 51 and the pipes 52, 53 are fully and easily accessible from outside the mill stand.

[0064] exist Figure 1-2 In the example shown, as described above, two cooling systems are provided, namely, one cooling system on each of the two faces of the mill stand, which are parallel to each other and perpendicular to the horizontal rolling direction Y.

[0065] Preferably, the two cooling systems are arranged symmetrically about the second vertical centerline plane of the rolling mill stand, and the rolling direction Y is orthogonal to the second vertical centerline plane.

[0066] In this case, coolant (usually water) can be supplied to the work rolls near both surfaces of the mill stand. However, it is best to operate only one of the two cooling systems to avoid the risk of overcooling the rolled product.

[0067] In a preferred, but not unique, variation, the hydraulic connection 47 includes at least one fitting 64 for connection to a corresponding first supply device 49.

[0068] At least one pipe fitting 64 is arranged inside the structure of the mill stand and has a washer 65 (e.g., having a flat and round shape) at its upper end. This washer is positioned tangent to the flat upper surface 70 of the structure. When the mill stand is raised to lock it in the corresponding mill compartment, the washer automatically adheres in a sealing manner to the corresponding hydraulic block for distributing coolant, which is arranged on the upper inner surface of the corresponding compartment. Therefore, the hydraulic connection can be ensured simply by lifting the mill stand with an actuator.

[0069] Specifically, the at least one pipe fitting 64 is arranged in the first surface cavity 40 of the structure. Figure 1 and Figure 2The tube 64 opens at the upper edge 55 of the structure from the transverse entrance side of the mill stand in the corresponding mill compartment. Therefore, the tube 64 is also easily accessible from outside the mill stand. Figure 1 In the diagram, the direction in which the mill stand is inserted into the corresponding compartment is indicated by arrow A.

[0070] This configuration of fitting 64 and gasket 65, on the one hand, avoids potential interference with the corresponding compartment of the mill during insertion or withdrawal from the stand, and on the other hand, eliminates the need for manual operator intervention to connect the hydraulic connection to the coolant supply circuit arranged in the mill stand.

[0071] Preferably, but not necessarily, the first supply device 49, the second supply device 50 and the third supply device 51 include a device having a spray nozzle or blade 54 provided with a groove facing at least the corresponding work rollers 3, 3'.

[0072] In one variation, these spray nozzles or blades 54 are arranged in an alternating manner relative to each other, or they have different orientations relative to each other, to prevent the respective coolant jets or blades from interfering with each other, thereby reducing the cooling effect.

[0073] Furthermore, for example, in the case of a jet nozzle, the axis of the jet nozzle can be completely oriented towards the interior of the groove to further improve cooling efficiency.

[0074] In the variant shown in the cross-sectional views of Figures 2a and 2b, the first supply device 49 includes or is composed of a device or block 49', which is fixed to the surface of the mill stand, for example by screws or other suitable fastening means, preferably located in a recess 69 on the surface.

[0075] A pipe 66 is provided in block 49', which connects to fitting 64 upstream and branches downstream, always within block 49', forming at least two additional pipes 67 and 68 that are transverse to pipe 66 and opposite to each other. In the example shown, only the other two pipes 67 and 68 are provided, which connect downstream to pipes 52 and 53 respectively, thereby connecting the first supply device 49 to the second supply device 50 and the third supply device 51 respectively.

[0076] Along other pipes 67, 68, one or more spray nozzles may be provided, which may be oriented differently from each other, at least facing the groove of the corresponding work roller 3.

[0077] The second supply device 50 and the third supply device 51 constitute the two ends of the cooling system, including or consisting of devices or blocks fixed to the surface of the rolling mill stand, for example by screws or other suitable fixing devices, preferably located in corresponding recesses on the surface.

[0078] In this case, each block is provided with at least one additional pipe that is connected upstream of the corresponding pipes 52 and 53.

[0079] For example, a single additional pipe may be provided, which is provided with one or more spray nozzles that may be oriented differently from each other, at least facing the grooves of the corresponding work rollers 3, 3'.

[0080] Referring to Figure 2, the distance between the two hydraulic connection devices 47 (measured parallel to the horizontal rolling direction Y) is set such that during the insertion of the mill stand into the mill compartment, the corresponding upper central abutment 22 of the compartment can traverse this distance. This abutment is fixed, and the wall 41 or coating element 73 will abut against it. In particular, the longitudinal extension length of the coating element 73 along the horizontal rolling direction is approximately equal to or greater than the longitudinal extension length of the upper central abutment 22.

[0081] When the mill stand is pulled out of the compartment, the distance between the two hydraulic connection devices 47 is also crossed by the upper central support 22.

[0082] Figures 8 to 10 An example of a rolling mill is shown, which includes multiple mill stands 1, 2 arranged sequentially along a rolling axis such that corresponding channels 5 are aligned to define rolling channels along the rolling axis.

[0083] Specifically, mill stands 1 and 2 are arranged adjacent to each other along the rolling axis, and the positions of the work rolls 3 and 3' of the odd-numbered mill stands 1 correspond to the positions of the work rolls 3 and 3' of the adjacent even-numbered mill stands 2 around the vertical axis V passing through the center of the channel 5. Figure 5 Rotate 180°.

[0084] Therefore, the odd-numbered mill stands 1 of the mill stands 1 and 2 have work rolls 3' with a vertical rotation axis X on the first side of the mill, which are parallel to the rolling axis, while the even-numbered mill stands 2 of the mill stands 1 and 2 have work rolls 3' with a vertical rotation axis X' on the second side of the mill, which are parallel to the rolling axis and opposite to the first side.

[0085] Advantageously, the rolling mill is provided with a frame 4, preferably a single frame, to accommodate mill stands 1 and 2 along the rolling axis. This frame is designed such that odd-numbered mill stands 1 can be inserted into frame 4 specifically in a direction transverse to the rolling axis and withdrawn from frame 4 only from the first side of the mill, while even-numbered mill stands 2 can be inserted into frame 4 and withdrawn from frame 4 specifically in a direction transverse to the rolling axis from the second side of the mill. In a preferred variant, these transverse directions coincide.

[0086] In stand 4, odd-numbered compartments are provided for odd-numbered mill stands 1 and even-numbered compartments are provided for even-numbered mill stands 2.

[0087] For all stands, the above-described construction of the frame and mill stand allows for minimizing the release stroke of adapters 34, 35, and 36 and restricts the downward rotation of adapter 36 on the stand exit side to a few degrees, thereby ensuring that the adapter can be used even without a universal joint.

[0088] Figure 11 and 12 The diagram shows a frame compartment without a stand, with adapters 34, 35, and 36 in the extended position, i.e., connected to the corresponding work rolls, and adapters 34, 35, and 36 in the retracted position, allowing the mill stand to be withdrawn.

[0089] Framework 4 also includes ( Figure 10 A first end wall 42 and a second end wall 43, the first end wall 42 being transverse to (e.g. or orthogonal to) the rolling axis and configured for the entry of the object or product to be rolled, and the second end wall 43 being opposite to, for example parallel to, the first end wall 42 and configured for the exit of the object or product to be rolled. The two end walls may be arranged perpendicular to the rolling axis.

[0090] In a preferred embodiment of the rolling mill, the following components are provided for replacing one or more rolling mill stands ( Figure 8-9 ): - A first side platform 12 located on the first side of the rolling mill, which is laterally arranged in the parallel arrangement in the frame 4, is connected in series to form at least one odd-numbered rolling mill 1 that is drawn out of the frame 4 by a conveying device, and supports at least one new odd-numbered rolling mill 1' to be inserted into the frame 4; - A second side platform 13 located on the second side of the rolling mill, which is laterally arranged in the frame 4, is connected in series with at least one even-numbered rolling mill 2 that is drawn out of the frame 4 by a conveying device, and supports at least one new even-numbered rolling compressor 2' to be inserted into the frame 4.

[0091] To allow the mill engine to be withdrawn and inserted into the mill stand of this invention, the following device may be provided, for example: The first actuator 20, located in the odd-numbered compartments of frame 4, is used for inserting and withdrawing the odd-numbered mill stands, and The second actuator 21, located in the even-numbered compartments of frame 4, is used for inserting and withdrawing the even-numbered mill stands.

[0092] These actuators 20, 21 can be, for example, hydraulic actuators or electromechanical actuators.

[0093] The first actuator 20 and the second actuator 21 preferably hook the respective mill stands 1, 2 to be pulled out of the frame 4 individually or in groups, move them on the relevant side platforms 12, 13, and are configured to hook the new mill stands 1', 2' to be inserted into the frame 4 individually or in groups, move them from the relevant side platforms 12, 13.

[0094] As examples of actuators 20 and 21 used for withdrawing and inserting the mill stand into frame 4, Figure 9 A bracket 37 is shown, which is adapted to translate from a first position to a second position in a direction transverse to the rolling axis. The first position is distal to the frame 4 and located outside the associated platforms 12, 13 (with the rolling axis as a reference), while the second position is proximal to the side opening of the corresponding compartment of the frame 4.

[0095] In a variant, the bracket 37 is provided with a hook configured to hook one or two protrusions 39 (Figures 2 to 3) located on the vertical side of each mill stand, which is close to the work roll 3' having a vertical axis of rotation.

[0096] In the second embodiment of the rolling mill stand of this utility model, three axial contact elements 56, 57, and 58 are provided on each surface of the rolling mill stand perpendicular to the horizontal rolling direction Y. Figure 1 These contact elements are arranged at a 120° angular distance from each other relative to the center point of the surface, which is substantially located on the rolling axis of the mill once the stand is inserted into the corresponding compartment. These contact elements are adapted to receive axial thrust along the rolling axis on the first surface and to transmit axial thrust on the second surface by transferring the axial thrust from one mill stand to the next.

[0097] Preferably, the three axial contact elements 56, 57, 58 on the first face and the three axial contact elements 56, 57, 58 on the second face are arranged symmetrically about a second vertical centerline plane of the mill stand parallel to the first face and the second face.

[0098] More preferably, two of the three contact elements, 56 and 57, are arranged in the upper region of each face of the stand, symmetrical with respect to the first vertical centerline plane of the mill stand, the first vertical centerline plane being parallel to the rolling direction Y and perpendicular to the second vertical centerline plane, while the remaining axial contact element 58 is arranged in the first vertical centerline plane, in the lower region of each face of the stand.

[0099] Axial contact element 56 is closest to the entrance side of the mill stand in the corresponding mill compartment, while axial contact element 57 is furthest from the entrance side.

[0100] In a variation of the second embodiment, on each face of the frame, axial contact elements 56 and axial contact elements 58 have their own contact surfaces, which are preferably flat and arranged at a distance from the second vertical centerline plane. This distance is shorter than the distance between the contact surface of the axial contact element 57 and the second vertical centerline plane, so as to facilitate the uninterrupted insertion of the mill frame into the compartment.

[0101] However, a variation is not excluded in which the contact surfaces of all axial contact elements 56, 57, and 58 are equidistant from the second vertical centerline plane.

[0102] In all embodiments of this invention, the group consisting of three supply devices 49, 50, 51 and pipes 52, 53 protrudes from the flat surface of the corresponding face of the rolling mill stand to a lesser extent than the group consisting of the aforementioned three axial contact elements 56, 57, 58.

[0103] In Figures 1-4, the axial contact element is flat and circular, but other shapes besides circular are not excluded.

[0104] In a rolling mill in which the mill stand according to the present invention is inserted, a device for axial locking is provided, that is, a device for locking the mill stand within the frame 4 along the rolling axis.

[0105] Preferably, such as Figure 10 As shown, at least two thrust actuators 29 are disposed in the frame 4, located from the rolling stock. On the exit side of the rolling mill, i.e., on the second end wall 43, the thrust actuators are adapted to push the mill stands one after another in a direction preferably opposite to the rolling direction (indicated by arrow B) to lock the frame 4 against at least two fixed blocks 33 along the rolling axis. These blocks 33 are located on the inlet side of the object to be rolled in the mill, i.e., on the first end wall 42. Specifically, three thrust actuators 29 can be provided, adapted to push the mill stands one onto another at three axial contact elements 56, 57, 58, preferably in a direction opposite to the rolling direction, to lock the mill stands in the frame 4 along the rolling axis against three corresponding fixed blocks 33. However, the use of a single fixed block 33 is not excluded.

[0106] Furthermore, in a preferred variant, the elastic device 30 is disposed in the frame 4, arranged between the odd-numbered and even-numbered compartments of the frame 4, and adapted to transmit the thrust generated by the thrust actuator 29 by transferring the thrust from one mill stand to the next mill stand until the entire mill unit is locked against the fixed stop 33.

[0107] Therefore, in this variant, during axial locking, the axial contact elements 56, 57, and 58 of the two subsequent frames do not directly contact each other, but rather contact each other through the elastic device 30 (Figure 10).

[0108] This elastic device 30 is designed so that once the thrust actuator 29 fails, the mill stand returns to its initial insertion position in the frame 4, so that no friction is generated between adjacent mill stands 1, 2 during the step of withdrawing the mill stand from the frame 4.

[0109] In particular, the elastic device 30 may include ( Figure 10-12 Systems of resilient plates or abutments, for example, some cantilevered to the upper inner surface of the frame, while others cantilevered to the lower inner surface of the frame. Figure 11 and 12 As shown, for example, a group of elastic plates or elastic sheets 30 are arranged transversely to the rolling axis, especially when they are in a stationary configuration, they are arranged on a vertical plane perpendicular to the vertical plane containing the rolling axis.

[0110] Thrust actuator 29, such as a hydraulic cylinder, stacks mill stands 1, 2 from the exit side toward the inlet side of the mill. Each stand pushes the next stand through a system of elastic plates or sheets, which allow individual stands to be pulled out without friction once the axial lock is released, thus preventing displacement of the previous or next stand.

[0111] In the third embodiment of the rolling mill stand of this utility model, a lifting eye bolt 59 is provided at each upper corner of the structure. Figures 1 to 2 Alternatively, another suitable lifting ring or hook can be used to move the mill stand by crane. Advantageously, each eye bolt 59 is oriented; for example, it can be rotated inwards toward the structure, particularly toward the first surface cavity 40, from a vertical position (Fig. 1) to a substantially horizontal position (Fig. 2) to avoid interference when inserting the mill stand into the corresponding mill compartment. Once the mill stand is removed from the mill, the eye bolt 59 can be rotated back to its vertical position for movement by crane.

[0112] As described above, in order to lock the mill stand after it has been inserted into the corresponding mill compartment, the stand needs to be lifted into the compartment.

[0113] Specifically, during the process of inserting the mill stand laterally (preferably perpendicular to the rolling axis) into the mill compartment, the first wall 41 or the first coating element 73 abuts against at least one first central contact portion 22 provided on the inner surface of the compartment.

[0114] If configured, the second wall 41' or alternatively the second coating element 73' also abuts against at least one second central contact portion 22' disposed on the lower inner surface of the compartment.

[0115] Therefore, these center contact portions 22, 22' define the end of the mill stand's stroke during the insertion step into the mill stand.

[0116] The surface cavities 40, 40' allow the rack to move forward without interfering with the compartments until it reaches the central contact 22, 22'.

[0117] The central contact portions 22, 22' are positioned along a vertical plane close to the rolling axis, preferably at a certain distance from the rolling axis, which is less than the distance between the vertical plane containing the rolling axis and the vertical plane containing the vertical rotation axis X of the work roll 3'.

[0118] exist Figures 5 to 7 In the example, only one central abutment 22, 22' is visible on the upper and lower inner surfaces of the frame compartment.

[0119] It is possible that two or more central abutment parts can be set on the upper and lower inner surfaces of the compartment.

[0120] In the fourth embodiment of this utility model, at least two coating elements 48 (Figures 1 to 2) are provided in the upper surface 70 of the structure of the mill stand. The coating elements 48 protrude from the upper surface 70 to abut against corresponding upper abutment members 24 (Figure 7) provided on the upper inner surface of the mill compartment that houses the mill stand.

[0121] exist Figures 1 to 2 In the example shown, four coating elements 48 are arranged at the corresponding upper corners near the frame structure.

[0122] The coated element 48 can also be made of a material with greater hardness than the material of the mill stand structure to improve its durability and locking accuracy. Examples of available materials include steels such as C40, C50, and 42CrMo4, wear-resistant steels with a nominal hardness of 400-500 HBW (such as Hardox 400 or Hardox 500), and CORC®-g composite steel, whether or not they are surface hardened by heat treatment.

[0123] The shape of the coating element 48 can also be selected to facilitate its maintenance or replacement.

[0124] To achieve lateral locking of the stand within the corresponding mill chamber (i.e., transverse to the rolling axis), the mill chamber is also equipped with (Figure 5-7): - At least two lifting and locking actuators 23 are arranged on the lower inner surface of the compartment for lifting the mill stand after reaching the central abutment or the two central abutments 22, 22'; - and at least two upper abutment portions 24, arranged on the upper surface of the compartment, adapted to define the end of the lifting stroke of the mill stand, and thus define the abutment surface of each coated element 48.

[0125] Therefore, the mill stand is raised and abuts against the at least two upper abutment portions 24 at the coating element 48, so that the rolling position is always repeated and is not affected by wear of the rails, wheels or sliding devices used to pull out and insert the stand during the changeover process.

[0126] As an explanation, these lifting and locking actuators 23, such as hydraulic cylinders, can be operated by valves for each mill stand in order to ensure better synchronous control.

[0127] Preferably, the hydraulic cylinder is provided with a rod having a wedge-shaped end 31.

[0128] The mill stand also has at least two recesses 32 at its base. Figure 3 and Figure 6The shape of the recess 32 is complementary to the wedge-shaped end 31 of the corresponding rod. The wedge-shaped end 31 of the rod and the corresponding recess 32 are shaped such that the reception of the wedge-shaped end 31 in the recess 32, in addition to lifting, produces a slight lateral translation of the mill stand to keep it abutting against at least one central abutment 22, 22'. For this purpose, an appropriate gap exists between the width of the wedge-shaped end 31 and the width of the recess 32.

[0129] Preferably, refer to Figure 2 , Figure 3 and Figure 6 Four lifting and locking actuators 23 and four upper abutment parts 24 can be provided in the frame of the rolling mill chamber. They are respectively arranged in pairs on the first and second surfaces of the rolling mill stand and are symmetrically arranged with respect to the second vertical centerline plane of the aforementioned rolling mill stand, which is parallel to the first and second surfaces and perpendicular to the rolling axis.

[0130] Therefore, the following features can be incorporated into the structure of the rolling mill stand: - Four coating elements 48 protrude from the upper surface 70 of the mill stand structure and are arranged in pairs near the respective upper corners of the structure on the first and second surfaces of the mill stand, and are symmetrical with respect to the second vertical centerline plane; - and four recesses 32, which are located approximately at the corresponding four coating elements 48, and preferably have a shape complementary to the wedge-shaped end 31 of the corresponding rod.

[0131] In the fifth embodiment of this utility model, four wheels 60 are provided at the lower corner of the rolling mill stand. Figure 3 Each wheel 60 is mounted in a corresponding box 61, which is detachably fixed in a corresponding groove 90 in the lower edge of the structure.

[0132] Wheels 60 are mounted on the box 61 for easy replacement when worn, and all are identical to facilitate their production and assembly.

[0133] The four wheels 60 are also arranged in pairs on the first and second surfaces of the mill stand, and are symmetrical with respect to the second vertical centerline plane of the mill stand, parallel to the first and second surfaces, and therefore perpendicular to the rolling axis.

[0134] Preferably, each box 61 has an inverted T shape and is detachably fixed to the structure by a fastening device 62 (e.g., screws), thereby connecting the two arms of the T shape to the lower edge of the structure.

[0135] In a variation of the fifth embodiment, each cartridge 61 has a recess 32 at its bottom, which preferably has a wedge shape to accommodate a wedge-shaped end 31 that is complementary to the shape of the corresponding rod of the lifting and locking actuator 23. As shown in FIG3, the recess 32 may be arranged near the compartment that accommodates the corresponding wheel 60.

[0136] In a further variation of the fifth embodiment, at the lower edge of each face of the rolling mill stand, perpendicular to the horizontal rolling direction Y, at least one receiving slide 63 fixed to the structure is provided, for example, one receiving slide 63 is provided for each face. Figure 3 ).

[0137] The receiving slides 63 on the two sides of the rolling mill stand are arranged to be parallel to each other and perpendicular to the rolling direction.

[0138] Each receiving slide 63 extends longitudinally, has the shape of a basic flat plate, and is located between two wheels 60 on the corresponding face of the frame to keep the wheels 60 properly aligned along the corresponding slide rail 71 (Figure 6).

[0139] Preferably, the interval between the receiving slides 63 on the two sides is greater than or less than the interval between the wheels 60 on the first side and the wheels 60 on the second side of the frame.

[0140] The shape of the slide 63 can also be selected to facilitate its maintenance or replacement.

[0141] The receiving rail 63 can also be made of a material with greater hardness than that of the mill stand structure to receive the wheel 60 and ensure its proper placement on the rail, and also to improve its durability. Examples of available materials include steels such as C40, C50, and 42CrMo4, wear-resistant steels with a nominal hardness of 400-500 HBW (such as Hardox 400 or Hardox 500), and CORC®-g composite steel, whether or not surface-hardened by heat treatment.

[0142] The optional features described above in each embodiment of the rolling mill stand of this utility model may be combined with each other, in whole or in part, in another embodiment.

Claims

1. A rolling mill stand for rod-shaped objects, comprising a structure in which three work rolls (3, 3') are arranged at 120° to each other, thereby defining a channel (5) for rolling the rod-shaped object in a horizontal rolling direction (Y). in, One of the three working rollers (3') has a vertical axis of rotation (X); The structure of the mill stand is characterized by having a first surface cavity (40) at the top, the first surface cavity opening at the upper edge (55) of the structure and being disposed on the entrance side of the mill stand, transverse to the rolling axis of the mill in the corresponding mill compartment; The first surface cavity (40) is disposed on the inlet side of the mill stand, opposite to the side where the work roll (3') is located. The work roll (3') is disposed on the side with respect to the first vertical centerline plane of the mill stand. The first vertical centerline plane is parallel to the horizontal rolling direction (Y). Furthermore, the first surface cavity (40) is defined by a first wall (41) near the first vertical centerline plane, the first wall (41) being adapted to abut against at least one corresponding first center abutment (22) disposed on the upper part of the mill compartment. The length of the first wall (41) is equal to at least 2 / 3 of the thickness (T) of the mill stand as measured along the horizontal rolling direction (Y).

2. The mill stand according to claim 1, wherein the bottom of the structure is provided with a second surface cavity (40'), the second surface cavity (40') opening at the lower edge (55') of the structure, the lower edge (55') being on the same side as the upper edge (55), and the second surface cavity (40') being defined by a second wall (41') near the first vertical centerline plane, the second wall (41') being arranged on the same plane as the first wall (41) and adapted to abut against at least one corresponding second center abutment (22') disposed at the lower part of the mill compartment. in, The length of the second wall (41') is equal to at least 2 / 3 of the mill stand thickness (T) measured along the horizontal rolling direction (Y), and is equal to the length of the first wall (41).

3. The rolling mill stand according to claim 2, wherein, A first recess (72) is provided on the first wall (41), and a first coating element (73) is integrally fixed in the first recess (72) and protrudes into the first surface cavity (40). The first recess (72) is adapted to abut against the first central abutment (22). Wherein, a second recess (72') is obtained on the second wall (41'), a second coating element (73') is integrally fixed in the second recess and protrudes into the second surface cavity (40'), and the second recess (72') is adapted to abut against the second central abutment (22').

4. The rolling mill stand according to claim 3, wherein, The length of the first coating element (73) and the length of the second coating element (73') are equal to at least 1 / 3 of the mill stand thickness (T) measured along the horizontal rolling direction (Y).

5. The mill stand according to claim 3, wherein one outermost part of the first coating element (73) protrudes into the first surface cavity (40) relative to the first recess (72), the outermost part of the first coating element (73) serving as an abutment surface and arranged parallel to the first vertical centerline plane of the mill stand; in, One of the outermost parts of the second coating element (73') protrudes into the second surface cavity (40') relative to the second recess (72'), the outermost part of the second coating element (73') serving as an abutment surface and arranged parallel to the first vertical centerline plane; The outermost or contacting surfaces of the first coating element (73) and the second coating element (73') are arranged on the same vertical plane parallel to the first vertical centerline plane.

6. The mill stand according to any one of claims 3 to 5, wherein the material of the first coating element (73) and the material of the second coating element (73') have greater hardness than the material of the structure of the mill stand.

7. The mill stand according to claim 2, wherein the first surface cavity (40) is obtained along one half of the flat upper surface (70) of the structure, and another surface cavity is obtained in the other half, wherein the upper end of the shaft of the work roll (3') having a vertical axis of rotation protrudes from the flat upper surface (70); The second surface cavity (40') is obtained along half of the flat lower surface (80) of the structure.

8. The rolling mill stand according to claim 1, wherein, A cooling system is provided on at least one surface of the mill stand that is perpendicular to the horizontal rolling direction (Y); The cooling system includes, - A hydraulic connection device (47) for introducing coolant into the mill stand, the hydraulic connection device being disposed on the upper part of the structure. - A set of three supply devices (49, 50, 51) for supplying coolant from the hydraulic connection device (47) to each work roll (3, 3'), each supply device (49, 50, 51) being arranged close to the corresponding work roll (3, 3') on at least one surface; The first supply device (49) is located close to and connected to the hydraulic connection device (47), and two pipes (52, 53) are arranged on at least one surface, branching out from the first supply device (49) and connecting the first supply device (49) to the second supply device (50) and the third supply device (51) respectively.

9. The mill stand according to claim 8, wherein the hydraulic connection device (47) comprises at least one fitting (64) for connection to the first supply device (49), the at least one fitting (64) being disposed inside the structure and having a gasket (65) at its upper end, the gasket being disposed at a tangential position on the flat upper surface (70) of the structure such that when the mill stand is lifted into the interior of the corresponding mill compartment, the gasket is sealed to a corresponding coolant supply pipe disposed on the upper inner surface of the corresponding compartment.

10. The rolling mill stand according to claim 9, wherein, The at least one pipe (64) is arranged within the first surface cavity (40).

11. The rolling mill stand according to any one of claims 8 to 10, wherein, The first supply device (49), the second supply device (50) and the third supply device (51) include spray nozzles or blades (54) that are at least facing the grooves of the respective work rollers (3, 3') and are arranged in an alternating manner relative to each other or oriented in different directions relative to each other to prevent the respective coolant spray streams or blades from interfering with each other. In the case of a spray nozzle, the axis of the spray nozzle is oriented toward the interior of the groove.

12. The rolling mill stand according to claim 1, wherein, On each face of the mill stand perpendicular to the horizontal rolling direction (Y), three axial contact elements (56, 57, 58) are provided, the three axial contact elements are arranged at an angular distance of 120° from each other, and are adapted to receive axial thrust along the rolling axis of the mill on a first face and transmit the axial thrust along the rolling axis of the mill on a second face, transferring the axial thrust from one mill stand to the next mill stand; The three axial contact elements (56, 57, 58) on the first surface and the three axial contact elements (56, 57, 58) on the second surface are arranged symmetrically about the second vertical centerline plane of the mill stand parallel to the first and second surfaces.

13. The mill stand according to claim 12, wherein two of the three contact elements (56, 57) are arranged in the upper region of each face, symmetrical about the first vertical centerline plane of the mill stand, the first vertical centerline plane being perpendicular to the second vertical centerline plane, while the remaining axial contact element (58) is arranged in the lower region of each face at the first vertical centerline plane.

14. The rolling mill stand according to claim 12 or 13, wherein, On each face, the axial contact element (56) closer to the entrance side of the mill stand into the corresponding mill compartment and the axial contact element (58) arranged in the lower region of the face at the first vertical centerline plane have corresponding contact surfaces, the contact surfaces being arranged at a distance from the second vertical centerline plane, the distance being less than the distance of the contact surface of the remaining axial contact element (57) from the second vertical centerline plane, the remaining axial contact element (57) being the farthest from the entrance side of the mill stand.

15. The rolling mill stand according to claim 1, wherein, At each upper corner of the structure, there are eye bolts (59) for moving the mill stand by a crane; and each eye bolt (59) is foldable toward the inside of the structure to avoid interference during the insertion of the mill stand into the corresponding mill compartment.

16. The rolling mill stand according to claim 1, wherein, At least two coating elements (48) are provided on the upper surface (70) of the structure of the rolling mill stand. The at least two coating elements (48) protrude from the upper surface (70) to abut against a corresponding upper abutment (24). The corresponding upper abutment (24) is provided on the upper inner surface of the rolling mill compartment that accommodates the rolling mill stand and defines the end of the lifting stroke of the rolling mill stand. Four coating elements (48) are provided, respectively arranged near the corresponding upper corners of the structure.

17. The rolling mill stand according to claim 1, wherein, Four wheels (60) are provided at the lower corner of the structure, wherein each wheel (60) is installed in a corresponding box (61), the box (61) being detachably fixed in a corresponding groove (90) in the lower edge of the structure; Each of the boxes (61) has an inverted T shape and is detachably fixed to the structure by means of a fixing device (62) that connects the two arms of the inverted T shape to the lower edge of the structure.

18. The rolling mill stand according to claim 17, wherein, At the lower edge of each face of the mill stand, perpendicular to the horizontal rolling direction (Y), at least one receiving slide (63) fixed to the structure is provided, each receiving slide (63) being located between two wheels (60) on the corresponding face to keep the wheels (60) aligned along the corresponding track; The distance between the receiving slides (63) on the two sides is greater than or less than the distance between the wheel (60) on the first side and the wheel (60) on the second side.

19. The mill stand according to claim 17 or 18, wherein each box (61) has a recess (32) at its bottom for receiving a wedge-shaped end (31) of a corresponding rod of a lifting and locking actuator (23) of the mill stand, the wedge-shaped end (31) having a shape complementary to the recess (32), the lifting and locking actuator (23) being disposed on the lower inner surface of the mill compartment; The recess (32) can be arranged adjacent to the compartment that houses the corresponding wheel (60).

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